Method and apparatus with a release thawing station for producing frozen confectionery bodies

ABSTRACT

In the production of edible ice bodies moulded and frozen in moulds it is required to convey heat to the outsides of the moulds in order to enable a demoulding of the bodies upon release thawing thereof, this traditionally being effected through warm water. With the invention it has been realized that for both the production and the quality of the ice bodies there are important advantages connected with the use of hot steam for the release thawing.

The present invention concerns a method for making frozen confectioneryproducts, especially edible ice bodies, which are frozen while they arein supporting contact with a support surface like a mould or a supportplate which is subjected to a short-period heating by a heating mediumfor liberating the frozen product. Generally, when using common freezingtechnique the products will freeze on to the surfaces they are incontact with. In some productions the frozen products may be detached bymechanical scraping, but it is more common that they are loosened byheating the contact surface, which is particularly relevant withdecidedly moulded products. Normally the contact surfaces will be goodheat transmitters because they are used actively in the freezingprocess, and therefore they are also relative-ly easy to heat up forachieving a sufficient melting loose of the product surface frozen on tothe contact surface.

In production apparatus for moulded edible ice bodies it is common toplace the freezing moulds in rows and projecting downward from uppersupport lamellar plates which in chain formation are conveyed over afreezing bath with the freezing moulds projecting downward into thebath. As the lamellar plates reach the outlet end of the bath they arelifted up from it for a subsequent lowering into a bath with warm water,where they subsequent to an additional short forward run are ready toliberate the products.

By the present invention it is found possible to indicate a method bywhich the melting loose may be performed in an even more advantageousway, i.e. both faster and more uniformly. For an effective melting looseit is required that all part areas of surfaces frozen solid are melted,and there may very well appear differences in the degree of freeze insuch a way that for one or more part areas it is necessary with moreheat for melting than in other part areas; in this way, the run throughthe warm water bath or in a loading zone for warm air has to besufficiently prolonged in order that also the more heat demanding areaswill get to thaw and this implies both a relatively long run and anunnecessary extensive melting of the surface areas that are thawed loosein the first place.

By the invention is has been observed that by using hot steam as thawingmedium surprisingly good results with respect to uniformity, speed, andenergy consumption have been achieved. At the outset there is used anannular nozzle which is utilized with a fast upward and downwardmovement for sending jets of hot steam (100-150°) directly against theouter wall of a cold ice lolly mould, whereby the ice lolly may befreely drawn up after a period in the magnitude of 1 second. We arespeaking of an extremely effective heat transmission produced by ainstantaneous phase shift from gas to ice/liquid phase at the contact ofthe hot steam with the cold mould wall parts maybe having a temperaturefrom -20° to -30°, whereby a high local vacuum is created, carrying withit new steam with high speed, i.e. with the speed of sound. Thereby thewarming up of the moulds becomes self-increasing.

An important fact is that hereby self-equalizing of the warming up willtake place, since colder areas will automatically attract more steamthan less cold areas. Furthermore, such a heat accumulation in the outerlayer of the mould will take place so quickly that during a last stageof the thawing the heat will be distributed inwardly in a way almostcontrolled by demand, possibly after termination of the heat supply.With certain moulds it is hereby possible to work with an active warmingup period of about 0.1 second, with an effective demoulding a few tenthsof a second thereafter.

Even though the heat transmission in the moulds is not completelyuniform with the said short thawing period there will no time for anyfurther melting of the parts of the surfaces of the product situated atthe areas with the highest heat transmission ability, and the length ofthe thawing zone, which conventionally cf. the example hereinabove is 12lamellar widths, may be reduced to a single lamellar width, a fact whichshortens the overall length of the apparatus or increases its capacity.

The heat energy used for the thawing is minimized because it is only themoulds that are heated, which also has the consequence that thesubsequent renewed cooling only requires recooling of the moulds and notof the other moved parts. Thereby about 10-15% cooling power may besaved. The heat supply may easily be stopped and minimized by regulatingthe steam pressure.

Since the hot steam is sterile the method will hygienicallyadvantageous, and besides that the system may be applied forsterilization of the moulds and the lamellas in that by slowing the rateof work of the apparatus when running idle it is possible to utilize thesteam for heating these parts to 100°.

Normally the ice factories in question will already have a steaminstallation and therefore the invention will mean low investment andoperating costs.

In ice making machines using cold air for freezing the products theinvention may be realized in a simple and advantageous way in that thesaid annular nozzle may be utilized directly in the freezingcompartment, since the energy supplied for thawing loose will beconcentrated on the moulds in such a way that the direct heat exchangewith the freezing air will be minimal. Thereby no separation of thecompartment between the freezing and the thawing sections will benecessary, and the occurring energy waste will be rather small.

It is important to note that the use of the said annular nozzleindicates a functional ideal which in an acceptable way may be givenfree in practice. So if working in a usual way with transverselypositioned rows of moulds in a conveying system it is a favourableopportunity just to use two mutually oppositely situated nozzle beamswhich then may service a whole row of moulds at a time. Preferably thereis utilized a box-shaped body which uppermost has nozzle outlets or itsinside and which at the bottom has a connection for a suction source.

The invention will be explained in the following with reference to thedrawing, on which

FIG. 1 is a schematic overview of an ice production plant,

FIG. 2 is a perspective view of some freezing moulds therein with aschematically shown thawing unit according to the invention,

FIG. 3 is a more detailled sectional view of a such unit in a slightlymodified form,

FIG. 4 is a schematic perspective view corresponding to FIG. 2, but of achanged embodiment of the freeze moulds and the means for thawing loose,

FIGS. 5 and 6 are sectional views for illustrating the working area ofthe thawing means, and

FIG. 7 is a schematic sectional view showing further embodiments.

The plant shown on FIG. 1 comprises an apparatus housing 2, in which ina not shown way there is conveyed a belt with downwardly projectingfreezing moulds which are filled with relevant confectionery or ice massin a filling station, whereafter the moulds when passing a freezing zoneare cooled for an initial freezing of their contents, so that in anaction station 6 carrying or handling sticks or pins may be placed inthe semifrozen bodies in the moulds. These are then subjected to furthercooling in the freezing zone, and when the moulded bodies are frozen toa desirable degree they come to a thawing station 8, wherein the mouldsare warmed up sufficiently for freely drawing up the moulded bodies fromthe moulds, which action may take place in the same or in a subsequentstation 10. Thereafter the moulds are returned to the filling station,which is symbolically marked as return station 12, which, however, mayalso represent a mould cleaning station.

In the present connection the thawing station 8 is in focus and it isreally without significance how the plant is designed besides that. Thesaid support belt may extend around in the horizontal or vertical plane,and the mould freezing may take place using cold air or moreconventionally by the use of freeze brine.

In FIG. 2 it is implied, that the shown freezing moulds 14 may be placedas rows on transversely positioned support lamellar plates 16 conveyedin a beltwise manner in the direction shown with arrow A. In regularproduction facilities there is used a large number of freezing moulds,so that it is possible to work with a production capacity of typically20-40.000 units per hour.

Cf. FIG. 2 the lamellar plate 16¹ shown with punctuated lines withcorresponding freezing moulds 14¹ has reached a position in the thawingstation 8 in which according to the invention there is placed anunderlying transverse beam 18 carrying a number of upright standingcylindrical bodies 20 with such a shape and position that these bodiescan be slided upwardly for confining the respective freezing moulds 14¹by raising the transverse beam 18 or possibly by a correspondinglowering of the lamellar plate 16¹.

The transversal beam is connected to a supply pipe 22 for hot steam froma steam source 24 together with a drain pipe 26 leading to an exhaustfan 28 via a steam trap 30. The cylindrical bodies 20 are shown asdouble walled cup bodies with an upper annular row of nozzle holes 32 inthe inner wall. These holes are in a not shown way connected to thesteam source 22 via a valve 23, and in the bottom of the cup bodiesthere is a connection to the suction pipe 26.

The transversal beam 18 may in this way be raised for achieving that thecup bodies 20 are slided upwardly for accomodating the moulds 14¹, andif or when the valve 23 is opened hereby the said steam heating of themoulds will take place during the raising of the ring of nozzle holes 32which will send jets of hot steam, e.g. at a pressure of 3 bar, directlyagainst the mould walls. This treatment may continue or be repeatedduring the subsequent lowering of the transverse beam, but depending onthe raising/lowering speed of the transversal beam it may be sufficientto keep the valve 23 open only during either raising or lowering. Thesuction from the pipe 26 counteracts pressure accumulation in theprocess compartment as well as it sucks up occurring condensate.

Immediately hereafter the ice bodies are drawn up from the moulds 14¹ bylifting the mounted sticks, whether these are permanent handle sticks orspecial carrying pins that are pulled out in a subsequent station fromthe ice bodies for automatic returning to the insertion station 6.

As implied in the above by using transversely placed rows ofmoulds--i.e. just as the case is in FIG. 2--it is possible to abstainfrom utilizing the individual cup bodies 20, in that instead an upwardlyopen box structure may be used which in a corresponding way act on themoulds only from the respective opposite longitudinal sides, and such aunit is shown in section in FIG. 3. On the hollow transversal beam 18there is mounted a top section 36 and a box body 38 projecting upwardtherefrom, the longitudinal sides of which body 38 are made up of doublewalls 40 connected at the bottom to longitudinally extending ducts 42 inthe top section 36, while they at the top have inwardly facing nozzleholes or slits 44. The ducts 42 are connected with the steam supply 22,and at the bottom they have some minor holes or slits 46 for drainingcondensate from the inner compartments in the double walls. The bottomof the box body 38 is communicating with the hollow compartment in thebeam 18 through a slot 48 and thereby also with the suction pipe 26.

In this embodiment there will not appear any steam jets directly againstthe narrow sides of the moulds 14¹, but as mentioned before the coldsurfaces in question will even suck the steam supplied to the spacesbetween the moulds to themselves, whereby the efficiency becomes verygood anyway.

In the embodiment shown on FIG. 4 the tranversely positioned supportplates 16, cf. FIG. 2, are made with indentations 50 for forming mouldsfor spheric ice bodies 52 without inserted sticks. When the plates 16reach the thawing station they are turned 180° and are placed on asupport plate 54 above which there is placed a thawing unit 56 to belowered over the moulds 50 now facing upwards. Furthermore, in thisstation there is provided not shown means for lifting the plates 16.

Inside the unit 56 there is provided a device 58 as shown more closelyin FIG. 5 for each of the moulds 50. This device has a top section 60with connections 62 and 64 for the steam pipe 22 and for pressurized airfrom a controlled air valve 66, respectively. The top section 60 has alower boring 68 accomodating an upward projecting neck piece 70 on alower shell section 72 that is shaped approximately corresponding to theoutside of the mould 50, but just slightly larger than this. Around thelower part of the neck piece 70 in the top section 60 there is shaped arecess 74 which through a drilling 76 is communicating with the steamsupply 62. The shell body 72, 70 is made with an annular abutment 78 forsealingly abutting against the lower outer edge of the top section 60,i.e. it will be able to receive otherwise shaped shell bodies if onlythese are designed in a standardized way at the top. The recess 74 willthen be closed downwards by means of an upper part of the shell piece72, and exactly in this some holes 80 for downward steam jets from therecess 74 are drilled.

At its lower annular edge the shell part 72 has a downward facingsealing ring 82 which by lowering the whole device may provide a sealingabutment against the presently upward facing underside of the mouldplate 16 outside around the mould 50. Between the mould edge and thesealing area in question there is provided some holes or slits 84 in theplate 16 for permitting evasion of air and steam from the compartmentdesignated 86 between the shell part 72 and the mould 50 when steam isblown down through the holes 80.

The neck piece 70 is provided with a central boring in which there isaccomodated a hollow pin 88 with a lower main section 90 provided with adownward facing sealing ring 92 around a central passageway 94 in thepin 88. The ring 92 is intended for abutting against the upper centralarea of the upwardly bulging mould 50 which just at this point has asmall hole 96, so small that in the normal position of the mould it willnot allow an outflow of the viscous freeze mass initially filled intothe moulds 50. The hollow pin 88 may be slided upwardly against theaction of a spring force.

When the unit 54, FIG. 4, has been lowered against the overturned mouldplate 16 the situation appears as shown in FIG. 5. When the steam valve23 is opened pressurized steam will be led to the compartment 86 throughdrilling 76, recess 74, and the holes 80 so that hot steam will sweepdown along the external side of the mould 50, while air and excessivesteam will evade through perforations 84 in the plate 16. While thisplate may be a very thin metal sheet of e.g. stainless steel, and themould sections 50 may be made of such a material and separately fastenedto the support plate 16, the operation of thawing loose itself mayhereby be performed extremely quickly so that it may be sufficient tosupply steam during 1/10 of a second.

For performing a secure, active removal of moulds pressurized air may besupplied through connection 64--or possibly even pressurized steam--tothe boring 68, whereby this pressure medium will act on the hollow pin88 with a downward force, causing a efficient sealing at the ring 92,and will be conveyed through the passageway 94 and the hole 96 in themould 50, so that the free-thawed ice body 52 will be acted on with apush downward of the mould 50. Such a pushing may take place when thesupport plate 16 is lifted more or less from the plate 54, e.g. just asindicated in FIG. 5, where the plate 54 is shown punctuated with a shortdistance below the plate 16.

Moreover, the main parts in question should then be lifted free fromeach other in order to permit further transport of both demoulded icebodies 52 and the left mould plates 16, and such a required detachmentis shown in FIG. 6.

It is a qualified part aspect of the invention that in the bottom of acasting or freezing mould a hole 96 may occur which do not allow outflowof the filled mass, but which later allow injection of a pressurizedmedium for expelling the cast or frozen body from the mould. Possiblythere may be utilized means for a temporary blocking of the hole so thatalso low viscous masses may be retained.

It should be mentioned that the device shown in FIG. 5 may very well beused in the reversed position, i.e. without overturning the moulds, ifonly supplementary means for picking up the ice bodies are used, e.g.carrying pins or sucking discs.

The invention relates to performing all kinds of tasks pertaining tofree-thawing including also the thawing free of ice products which in asimple way appear as lumps on a conveyed support belt, for example aftercutting off pieces from an extruded run of the material to be frozen. Ina subsequent, further freezing these pieces may very well adhere to thesupport belt, and a quick free-thawing may be achieved by supplying hotsteam to the underside of the belt on the relevant spot.

On FIG. 7 there is shown a slightly curved conveying track of a supportbelt 98, which also could be straight, with lumps 100 of ice mass laidthereon, and where the lumps 100 can occur situated either completely atthe outer side of the belt or in outer indentations 102 therein. At thefree-thawing station in question there is arranged a permanent or amovable screen 104 through which hot steam may be injected for achievinga very quick local warming up of the support surface for the ice bodies100 and thereby an effective liberation of these.

What is claimed is:
 1. An apparatus for making frozen confectionerybodies comprising a conveying device for freezing molds for moving themolds through a filling station and a freezing zone to a de-moldingstation, wherein thawing means for heating the molds to loosen thefrozen bodies for removal thereof from the molds, said thawing meanscomprising means for supplying hot steam to the exterior of the moldsand a mantle member surrounding at least one of the molds, a narrowspace being formed between the at least one mold and the mantle member,said mantle member having nozzle means connected with a hot steam supplysource for injecting hot steam into and along said narrow space towardsan outlet area from which air and steam are released from said narrowspace.
 2. The apparatus according to claim 1, in which said mantlemember is a substantially cylindrical structure having said nozzle meansarranged in a cross plane thereof, and in which motion means areprovided for effecting relative movement between the at least one moldand the mantle member in an axial direction of said mantle member. 3.The apparatus according to claim 2, in which said mantle member forms apocket for receiving the at least one mold through an open end thereof,said pocket having inwardly directed nozzle means in a wall adjacent tosaid open end, and a closed pocket end opposite to said open end beingoperatively connected with a suction source, said pocket being deepenough to receive the full length of said at least one mold.
 4. Theapparatus according to claim 1, in which said mantle member forms apocket cavity for receiving an entire mold, said pocket cavity having anapex, at which said nozzle means are arranged, the narrow space betweenthe mantle member and a mold inserted into said pocket cavity beingannular and extending along at least a substantial length betweenrespective end portions of the mold and the pocket cavity.
 5. A methodfor making frozen confectionery bodies by freeze molding in individualmolds and subsequently externally applying steam to the molds forloosening and removing the frozen bodies from the molds, comprising thesteps of:arranging at least one of the molds inside a mantle memberhaving inner surface portions located slightly spaced from outer surfaceportions of the mold so as to create a narrow space between the mold andthe mantle member, and injecting hot steam into and along the narrowspace towards an outlet therefrom, the steam expelling air from thenarrow space so as to intensify the heating effect of the steam on themold.
 6. The method according to claim 5, wherein said narrow spaceforms an annular zone about the at least one mold, and comprising thestep of axially displacing the mold relative to the mantle member insaid annular zone so as to effect thawing by a relative sweeping of thesteam along sides of the at least one mold.
 7. The method according toclaim 6, wherein the mantle member is a substantially cylindrical memberforming a pocket with an open end for receiving the at least one mold,said pocket having inwardly directed steam inlet openings in a walladjacent to said open end and a suction source connected to an oppositeend, the method further comprising the steps of inserting a mold intosaid pocket and retracting it therefrom, actuating steam supply to saidinlet openings during at least one of an insertion and retraction of themold, and effecting suction through said opposite end of the mantlemember at least whenever said steam supply is actuated.
 8. The methodaccording to claim 5, in which said mantle member forms a pocket cavityfor receiving an entire mold, and wherein said steam injecting step isperformed through an apex end of said cavity.
 9. The method according toclaim 5, in which the steam is injected as jets at a pressure of atleast 2 bar and a correspondingly elevated temperature.